1. Field of the Invention
The present invention relates to a motorcycle, such as a scooter-type motorcycle, wherein an engine is mounted on a body frame and a rear wheel is supported by a transmission case, provided between the engine and the rear wheel.
2. Description of the Relevant Art
Japanese Patent Laid-open No. Hei 3-213482 describes a scooter-type motorcycle. The motorcycle includes an engine main body, which is swingably supported by a body frame. An intake system is disposed between the engine main body and a seat.
The intake system swings together with the engine main body. As a result, a space must be provided between the engine and the seat for allowing the swing motion of the intake system. Therefore, the seat must be mounted at a relatively high position. Further, since the parts, associated with the intake system (such as cables, vacuum and gas hoses) are swung, the parts are subjected to increased wear and the service lives of these parts are degraded.
It is an object of the present invention to provide a motorcycle which addresses one or more of the drawbacks associated with the background art.
It is an object of the present invention to provide a motorcycle capable of mounting a seat at a relatively lower position.
It is an object of the present invention to provide a motorcycle that enhances the durability of parts associated with an intake system.
These and other objects are achieved by a scooter-type motorcycle having an engine including an engine main body disposed with the axial line of a cylinder bore directed forwardly. The engine main body is mounted on a body frame and a rear wheel is rotatably supported by a transmission case of a transmission provided between the engine and the rear wheel. The engine main body is non-swingably supported, at a position under a seat of the motorcycle, by the body frame. The transmission case is swingably supported by the engine main body. An intake port is provided in the engine main body in such a manner as to be opened upwardly. A throttle body is disposed with its axial line extending substantially in the horizontal direction and is connected, at a position under the seat, to the intake port via an intake pipe.
With a configuration in accordance with the present invention, since the engine main body of the engine is non-swingably supported by the body frame, the intake system including the intake pipe with its downstream end connected to the intake port of the engine main body and the throttle valve connected to the upstream end of the intake pipe is not swingable. As a result, it is possible to eliminate a space, for allowing the swing motion of the intake system, between the engine main body and the seat, and hence to mount the seat at a lower position. Further, since the parts associated with the intake system are not swingable, it is possible to improve the durability of these parts.
Also according to the present invention, a fuel injection valve, covered from above with the seat, is mounted to the intake pipe. With this configuration, it is possible to absorb any tapping noise caused by the fuel injection valve by the seat, and hence to suppress the tapping noise. Further, since parts associated with the fuel injection valve, such as fuel hoses continuous to the fuel injection valve are not swingable, it is possible to improve the durability of the parts associated with the fuel injection valve.
Also according to the present invention, the engine main body is supported by the body frame in such a manner that the axial line of the cylinder bore is tilted forwardly and upwardly. As a result, it is possible to ensure a space, for disposing auxiliary parts of the motorcycle (such as a gas or oil tank) in front of the engine main body while avoiding enlargement of the scooter-type motorcycle.
Also according to the present invention, a pair of cylinder bores arranged in the width direction of the body frame are provided in the engine main body. With this configuration, it is possible to increase the displacement of the engine while avoiding an increase in height of the main seat.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.